Method and System for Calculating Reference Value of Ultrasonic Sensor

2. The method of claim 1, wherein a larger reference value indicates a smaller deviation of sensing values for each position of the ultrasonic sensor.

3. The method of claim 1, wherein the first parameter is a frequency of the first ultrasonic signal used to generate the selected ultrasonic image.

4. The method of claim 3, wherein the second ultrasonic signal has a frequency corresponding to the first parameter.

5. The method of claim 1, wherein the second parameter is a reception delay time of the first ultrasonic echo signal corresponding to the selected ultrasonic image, from among the generated plurality of ultrasonic images.

7. The method of claim 6, wherein the contact device has no air gap between the first surface and the second surface.

8. The method of claim 7, wherein the contact device is a display panel.

9. The method of claim 1, wherein the reference value corresponds to a difference between a maximum pressure value and a minimum pressure value of the second ultrasonic echo signal within a specific time range based on the second parameter.

10. The method of claim 1, wherein the reference value corresponds to a median value of pressure values of the second ultrasonic echo signal within a specific time range based on the second parameter.

12. The system of claim 11, wherein a larger reference value indicates a smaller deviation of sensing values for each position of the ultrasonic sensor.

13. The system of claim 11, wherein the first parameter is a frequency of the first ultrasonic signal used to generate the selected ultrasonic image.

14. The system of claim 13, wherein the ultrasonic sensor transmits the second ultrasonic signal with a frequency corresponding to the first parameter.

15. The system of claim 11, wherein the second parameter is a reception delay time of the first ultrasonic echo signal used to generate the selected ultrasonic image.

17. The system of claim 16, wherein the contact device has no air gap between the first surface and the second surface.

18. The system of claim 17, wherein the contact device is a display panel.

19. The system of claim 11, wherein the reference value corresponds to a difference between a maximum pressure value and a minimum pressure value of the second ultrasonic echo signal within a specific time range based on the second parameter.

20. The system of claim 11, wherein the reference value corresponds to a median value of pressure values of the second ultrasonic echo signal within a specific time range based on the second parameter.